Rotating kiln



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and accompanying material at the other end.

Patented dan. 9, 1923.

HENRY H. HINDSHAW, 0F ST. PAUL, MINNESOTA.

ROTATING KILN'.

Application filed June 24, 1921. Serial No. 480,101.

To all whom t may. concer/m:

.Be it known that I, HENRY H. HINDSHAW, a citizen of the United States, residing at St. Paul, in the county of Ramsey and State of Minnesota, have invented certain newv and useful Improvements in Rotating Kilns; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as Will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a rotating kiln, and particularly to a kiln of a basic reducing type adapted to heat and reduce Acertain kinds of ore.

Roasting furnaces which function to add oxygen to the ore are generally known as acid kilns or furnaces and those which extract oxygen are generally referred to as basic kilns. v

There exist large quantities of ore bearing rock containing in the aggregate from 25% to 40%l of iron and it has been difficult to separate the ore therefrom. The applicant has invented a novel process for separating certain of these low grade ores from the accompanying material by crushing the same and then reducing it at a high temperature Without the presence of air, the ore being intimately mixed with some fuel, such as eat.

It is an object of this invention to provide a kiln in which this process can be easily and efliciently carried out, and which kiln is designed to receive the mixed ore and fuel at one end and to discharge the reduced ore It is a further object of the invention to provide such a kiln having means at one end by which lthe heat is directed into the kiln and having means at the other end for drawing off the products of combustion and also for inducing the heat from the heating means to act upon the material throughout the kiln.

These and other objects and advantages of'the invention will become apparent from the following description made in connectiornwith the accompanying drawings, in which like reference characters refer to the same parts throughout the different views, and in Which- Fig. 1 represents a longitudinal central `at its upper side for this purpose.

run upon bearing rollers supported in suitable brackets mounted on spacedpiers. The kiln is arranged to have an inclination downwardly .toward the discharge end and this inclination is approximately at a slant of one unit drop to fifteen in length. Thel kiln is providedwith a bushing 6 disposed centrally in its upper end, which has flanges thereon engaging the end and projecting slightly therebeyond. The kiln is illustrated as being driven by a gear ring 8 secured thereto, which ring meshes with a gear or pinion 9 which is driven by any suitable or convenient source of power. A fixed feeding tube 7 extends into the bushing 6 and is adapted to be connected with a mixing machine Which is a machine of ordinary pug- :mill type which thoroughly mixes the ground ore and the fuel.` The orewill be forced into tube 7,'a portion ofv a screw conveyor for this purpose being show n in said tube,which conveyor may be driven by any suitable means.

The kilnl is shown as open at its lower end and a movable fire brick wall or hood 10 mounted on a truck base 11 is disposed adjacent the end of the kiln. The wall or hood 10 carries a sealingc ring 12 into which the lower end of the kiln projects. which ringis omitted for a portion of the extent of the circumference of the kiln at the bottom thereof to form a discharge opening. The fuel nozzle for the burner 13 projects through the Wall 10 into the lower end of the kiln and is adapted to burn oil,'or gas, powdered coal or other fuel supplied thereto through the pipe connection 14 and to direct the flame into the Akiln.` The conduit or pipe* 14a. is disposed in the top portion of thekiln and is supported at its front end by the tube 7 which is exterrdlid is pipe is supported at its rear end by the hood 10 which is provided with an opening to accommodate the same. 'The pipe 142l is surrounded by another pipe l5 spaced.

therefrom, the space between the pipes pro-l The material is shown in the kiln in Fig. 24

as a, and this material will ordinarily be disposed largely at one side of the kiln and will slide down to maintain practically the same angle as the kiln rotates, the direction of rotation being indicated in this figure by the arrows. The material will discharge at the lower end of the kiln, as indicated in Fig. 1 and will drop into a pit 19 in the bottom of which is shown a conveyor 20 for conveying the same to any desired point.

The operation of the device is as follows:

The ore which has been properly crushed will be mixed with the peat or other fuel material and discharged into the kiln through the tube 7, being forced through this tube to provide an air seal. This ore will be disposed in the kiln, as illustrated in Fig. 2 and will gradually travel downward in the kiln asthe'same is rotated. The iame and the hot products of combustion from the burner 13 will be directed against the materiali-n the kiln and against the lining of the kiln and the material by contact of said flame and products and by con-1 tact with the heated lining will thus be heated to a high temperature. The fuel mixed with the material will burn and as there will be a dearth of oxygen in the kiln the fuel will unite with the oxygen present in the ore and will thus reduce the same. The combustion ofthe fuel from the burner 13, of course, is complete and considerable carbon dioxide will be formed by the combustion. The combustion of the fuel mixed with the ore will not be complete and considerable carbon monoxide will be generated. The fan 18 will be operated and the gas and products of combustion will, be drawn through the pipe 14a at the opening therein near the front end of the kiln. This will cause a draft lengthwise of thekiln at the lower portion thereof and will tend to bring the Haines and hot products of combustion into contact with the ore and kiln throughout the length thereof. `The material will thus be gradually heated and raised in temperature as it approaches the lower end of the kiln. The gaseous products of combustion will be drawn through the pipe 14a and fan.18 and these gases containing considerable carbon monoxide, can be burned to generate heat for any desired purpose. The pipe 14 will be kept suitably cooled by the circulation of water through pipes 16 and 17. The gases will follow the path indicated by the arrows and the pressure in the kiln being slightly below that of the atmosphere, there will be no tendency for the gases to pass out at the lower end with the calcined product,

From the above description it is seen that applicant has provided a simple and efiicient kiln for reducing the ore without the presence of much free air in contact therewith. The primary object of the operation which is the reduction of a non-magnetic ore to a magnetic ore, thus enabling the ore to be subsequently separated magnetically, being effectively accomplished. The kiln can be made very rugged in structure and has few parts requiring attention for maintenance or operation.

It will, of course, be understood that various changes may be made in the form, details and proportions of the apparatus without departing from the scope of applicants invention, which, generally stated, consists in the matter shown and described and set forth in the appended claims.

That is claimed is:

1. A reducing kiln comprising a long inclined cylindrical shell zfor receiving the material, means in one end thereof for directing heat into the kiln, and means adjacent the same end thereof for drawing off the products of combustion from the other end of the kiln.

2. A reducin kiln having in combination a long cy indrical shell inclined towards the discharge end, .said kiln being openoat the discharge end, a sealing wall adjacent the discharge end, a burner pro- "jecting into the open end of the kiln for directing heat into the kiln,4 a conduit extending through t-he open end of said kiln having an opening at the other end'of the kiln, and means for drawing .the products of combustion into said conduit and through the same out through the said open end.

3. A reducing kiln having in combination a long cylindrical shell inclined towards the discharge end, means for rotating said kiln,

means for feeding the material into 'the upper end of said kiln, said latter end being closed, heating means for the kiln disposed at the lower end thereof, -and means for drawing the heating gases and products of combustion from the upper end of the kiln out through the lower end thereof.

4. A reducing kiln having in combination a long cylindrical shell inclined toward the discharge end, means through which the material -is fed into the upper end of the shell centrally thereof, means for heating the kiln extending into the shell at the lower end thereof, a conduit supported in and adjacent the. top of the kiln having an opening near the upper end thereof, means for drawing products of combustion through said conduit, and means for cooling said conduit.

5. A reducing kiln having in combination a cylinder inclined toward the discharge end7 the upper end of said cylinder being closed except for a central opening, means through which material is fed through said' opening into the upper end of the cylinder said material sealing said opening7 the lower end of the cylinder being open, a movable hood disposed adjacent to the lower end of the cylinder having a sealing ring thereon disposed closely adjacent the cylinder throughout the side and upper portions of its circumference, means extending through said Wall into the lower end of the cylinder for heating the kiln, and means extending through said hood to the upper end of said cylinder for drawing off the products of combustion from .the upper end of the cylinder and out through said hood.

6. A reducing kiln comprising a long cylindrical container, means for supporting and rotating the same in an inclined position, the. upper'end of the container being closed except for an entrance conduit for the material and the lower end of the cylinder being open, a member disposed adjacent the lower end of the cylinder to close the same but spaced therefrom atthe lower portion to provide a discharge outlet7 means carried by said member and extending into the container for heating the material therein, and means extending through said member and into the upper end of the container for drawing ofi' the products of .combustion from the upper end of the container through the lower end thereof.

7. A reducing kiln comprising an inclined rotating shell closed at the upper end except for a feeding conduit, means for forcing the material through said conduit to provide an air seal, means extending into the lower end of the shell to heat the same, exhaust means disposed outside of the lower end of the kiln and means connected thereto passing into the kiln and terminating therein adjacent the front end thereof for carrying off the products of combustion from the upper end of the kiln and through the lower end thereof.

In testimony whereof I affix my signature.

` HENRY H. HINDSHAW. 

